It is generally agreed under the United Nations Framework Convention on Climate Change (FCCC) that there is a need to reduce the CO.sub.2 content of the atmosphere. The present invention may enhance the global environment by slowing potentially harmful changes to the climate due to increases in atmospheric CO.sub.2, a so-called greenhouse gas. The method may allow CO.sub.2 to be removed from the atmosphere for centuries and increase fish stocks for consumption by peoples of developing countries. Cost efficient fossil fuel may therefore be burnt while their by-product, CO.sub.2, is put to use rather than dumped into the atmosphere.
The natural process by which carbon dioxide present in the ocean is sequestered is known. (Andersen, N. R. and A. Malahoff, 1977: The fate of fossil fuel CO.sub.2 in the ocean. Plenum Press, N.Y., 749pp.). When atmospheric carbon dioxide dissolves in the ocean it exists in an ionic form and is taken into the bodies of marine phytoplankton through the process of photosynthesis. The phytoplankton eventually perish through age or are grazed by zooplankton. The resulting dead or excreted biomass then falls to lower levels of the water column where it is broken down by bacteria which re-release the carbon into the water column. However, typically 10% of the biomass escapes bacterial decomposition and falls to the ocean depths thereby effectively sequestering the carbon from the atmosphere.
It has been speculated that about 20% of ocean surface waters are deficient in trace nutrients required for phytoplankton growth. Martin et al (Nature, Vol. 371, pgs. 123-128) observed an increase in phytoplankton populations when iron was added to the sea surface in areas where phytoplankton numbers were low.